We have determined the crystal and molecular structures of the following Cu(II) complexes: Cu2 citrate.2H2O; Cu(l-methionine)2; and Cu-D-penicillaminedisulfide.9H2O. Crystallography studies are in progress for the following Cu(II) complexes: Cu(NH2CH2CH2SCH3). ClO4; Cu(BuSCH2CH2SBu)Cl2;Cu (BuSCH2CH2SBu)2 (ClO4)2; Cu(O3SCH2CH(NH2)CO2). 4H2O; and Cu(O2CCH2CH2SCH2CH2CO2-). (pyridine).H2O. The nature of Cu(II)-thioether bonding is being characterized by crystallographic, nmr line-broadening, laser raman, infrared, and electronic spectral studies. The latter studies include identification of the thioether yields Cu(II) charge-transfer absorptions. Other work includes a study by C13 nmr techniques of Cu(II) interactions with bile salt conjugates, and the interaction of Cu(II) with penicillamine analogs such as HSC(CH3)2 CH2NH2, HSC(CH3) CH2N(CH2CO2H)2, etc.